Lab-made biosensors for fructose determination based on carbon nanomaterials

The use of dehydrogenase enzymes in electrocatalysis and electroanalysis has led to the development of effective biofuel cells and biosensors. One of the most fascinating features of some dehydrogenases is their ability to directly communicate with specific transducing surfaces, allowing direct electron transfer (DET) from specific enzymatic sites, with no use for redox mediators. Herein, the Fructose Dehydrogenase (FDH) ability to give DET has been studied towards different 0D, 1D, and 2D carbonaceous NMs (C-NMs) prepared in water-phase avoiding the use of solvents; carbon black (CB), biochar nanofibers (NF), mesoporous carbon (MS)and graphene nanoplates (GF) have been successfully nano-structured in water using liquid-phase exfoliation (LPE). C-NMs have been employed in combination with labmade sensors fabricated by a stencil-printing approach; this strategy enables the production of sensors in series inexpensively by using office-grade substrates (polymeric sheets) and instruments (cruft-cutting plotter). The C-NMs-based sensors were carefully characterized and resulted able to give DET with FDH. CB and MS showed higher performances and were thus selected for biosensor construction for fructose (FRU) determination. Via chronoamperometry CB and MS biosensors returned similar performances with sub-micromolar limits of detections (LODs≤0.35 μM); both biosensors exhibited good reproducibility (RSD≤4%, n = 3) and repeatability (RSD≤4%, n = 10). Finally, MS-FDH and CB-FDH biosensors were challenged for the selective FRU determination in honey, food beverage, and urine samples achieving good recoveries (116%-95%, n= 3); biosensor selectivity was successfully proved against several potential interfering species. This work opens new gates for the development of biosensors based on carbon materials, including from renewable sources, produce without the use of solvents. Moreover, herein is demonstrated how lab-made sensors can results more performing than commercial ones, offering captivating and within everyone's reach opportunities in the framework of the bioanalytical scenario.